OF ELLIPTIC POLARIZATION. 
289 
reasons which I have assigned were subsequently strengthened by new inquiries 
which at first threw great doubts over the views which M. Biot and I had taken 
of the subject, and finally convinced me of the rashness of our generalizations. 
The study of M. Fresnel’s fine discoveries respecting circular polarization 
enabled me to advance still further in the inquiry ; and having more recently 
resumed the investigation, I trust I shall now be able to present to the Society 
a satisfactory analysis of the singular phenomena exhibited in the action of 
metals upon light. 
Sect. I. On the action of metals upon common light. 
When we analyse with a rhomb of calcareous spar a ray of common light, 
reflected at different angles from a metallic surface, there will be observed in 
one of the images a defalcation of light, as if a portion of the incident ray was 
polarized in the plane of reflexion. This effect will be still more distinctly 
seen if we examine the system of polarized rings formed round the axes of 
crystals by means of the light reflected from metals. If the light had suffered 
no modification by reflexion, or if the metal reflected in equal quantities the 
light polarized in opposite planes, the rings would not be visible at all ; but it 
will be found that they are easily seen in the light reflected by all metals. 
They are most distinctly visible at an incidence of about 74°, at an average, 
and become fainter and fainter as the incidence exceeds or falls below that 
angle. They appear best defined in light reflected from galsena and metallic 
lead, and with least distinctness in light reflected from silver and gold, as 
shown in the following Table, in which the metals are arranged in the 
order in which they exhibit the rings most brightly, and consequently in the 
order in which they polarize the greatest quantity of light in the plane of 
reflexion. 
Galsena, 
Antimony, 
Bismuth, 
Grain tin, 
Lead, 
Steel, 
Mercury, 
Jewellers’ gold, 
Gray cobalt, 
Zinc, 
Copper, 
Fine gold, 
Arsenical cobalt, 
Speculum metal, 
Tin plate, 
Common silver. 
Iron pyrites. 
Platinum, 
Brass, 
Pure silver. 
2 p 2 
